ATHENS, Greece - Greek riot police stormed the Athens subway train depot before dawn Friday to enforce a government emergency order forcing striking staff back to work in an escalating standoff over new austerity measures.

Dozens of strikers had barricaded themselves in the depot in western Athens late Thursday, after the government issued a rare civil mobilization order under which workers refusing to return to work risk dismissal, arrest and jail time.

Metro staff have been outraged by plans to scrap their existing contracts as part of a broader reform to public sector pay, with their union saying the measure would subject them to a roughly 25 per cent pay cut. Their strike has left the capital without subway service for nine days.

Hammered by a financial crisis since late 2009, Greece has imposed repeated rounds of public sector salary and pension cuts in return for billions of euros in international rescue loans. The measures have led to a deep recession, now in its sixth year, and unemployment spiraling above 26 per cent.

Police broke through the gates and removed dozens of strikers in the pre-dawn raid, while rows of riot police blocked off roads leading to the depot to prevent hundreds of strike supporters who had begun gathering from getting to the facility.

No violence was reported, with the workers not putting up resistance. The police blockade of the surrounding area continued into the afternoon.

The government's civil mobilization order led to a swift backlash, with all other public transport workers declaring immediate strikes that stranded commuters and forced them to walk or take taxis home through a thunderstorm Thursday night.

Defending the government's decision to invoke a rarely-used law to end the strike, government spokesman Simos Kedikoglou insisted the new austerity measures must be implemented.

"We are a society, an economy, at a very difficult time," he said. "People can't ask for exceptions."

With all forms of public transport on strike in sympathy Friday, traffic slowed to a crawl through the city's main streets, with commuters taking twice or three times as long as normal to get to work.

Authorities distributed notifications of the civil mobilization order to metro workers, who are obliged to respond once they receive the document, but getting the subway system up and running again was expected to take time as safety checks also had to be carried out before trains could operate.

Kedikoglou estimated that trains would begin running again during the weekend.

The civil mobilization law, amended in 2007 to deal with "peacetime emergencies," has now been used nine times since the 1974 collapse of a military dictatorship in Greece - three of those in the past two years in strikes related to austerity measures imposed in return for international bailouts. Defying the order to return to work can lead to arrest and jail terms of between three months and five years.

Unions and the radical left main opposition Syriza party accused the government of using dictatorial tactics.

"It's a new coup against this country's constitution to mobilize working people on strike on the subway with military-style methods," Syriza lawmaker Dimitris Stratoulis said late Thursday.

Considered an extreme measure, use of the law usually sparks an outcry but does tend to end a strike. It has been used in the past to end a protracted strike by garbage collectors, with the government at the time citing public health concerns, and to end a fuel truck strike that had caused major gasoline shortages.

The strike has been met with a mixture of understanding and exasperation from commuters, many of whom are in a similar situation and are suffering cuts to their own income. Strikes in general are so widespread and frequent in Greece that they have become part of everyday life.

"I agree with the strikers," said Christos Bousios as he walked through central Athens. "They have their demands. People will be inconvenienced. With all strikes, it's people who end up paying. ... Those who complain about the strikes today are the ones who strike the next day and make other people's lives hard."

The Greek capital's metro, which opened in 2000, serves more than 700,000 passengers daily. It operates alongside an older network, bringing the capital's combined daily subway traffic to 1.1 million passengers, according to the operators.